I'm building a HLT from a cooler and am wondering how other people have mounted a thermocouple or RTD. I want to use the liquid tight RTD sensor from Auber, which has a 1/4" NPT thread. My original thought was to use a weldless sight glass kit from bargainfittings with a reducing bushing, but I have a thick walled cooler, and a 4" probe would presumably project only 1/2" into the cooler. Is this OK? I haven't been able to find either a 1/4" bulkhead that would work on a 1.25" thick cooler or a longer RTD probe at a reasonable cost.

Get a high end bulkhead from aquaticeco.com, say 1/2'', cut a hole w a holesaw for the od of the threads, and then a bushing to reduce to your 1/4'' npt. The high end bulkheads are worth it imo. Put the flange part of the bulkhead, where you want the gasket, on the inside. That way, no wort gets into the insulation in the cooler walls. This is also a robust way to add a drain for the wort.

It says it has left hand threads. Is this the outside thread that secures the bulkhead to the cooler?

That PVC fitting will very likely soften and fail at mash temperatures. I would also be worried about what chemicals it gives off at elevated temperatures. It might work marginally for awhile if it is not subjected to any significant stress, but it is not the way I would go.

I just realized that mine are polypropylene. Not sure where I got them now. I've used lots of the grey pvc (schd 80 but maybe not cpvc) ones from aquatic eco, but not one the mash tun (aquaculture hobby). I've got some spares around, maybe I'll drop one into some 170F water and see how soft they get. The pp ones work fine on the tun though....

Thanks Catt. Definitely don't want any chemicals leaching into my sparge water. I think I'll just try the sight glass option since I need one anyways. I was anticipating the need to stir the sparge water in some fashion to eliminate temperature stratification, so maybe it won't be such a big deal that the probe will only be projecting 1/2" into the vessel. We'll see....

I just realized that mine are polypropylene. Not sure where I got them now. I've used lots of the grey pvc (schd 80 but maybe not cpvc) ones from aquatic eco, but not one the mash tun (aquaculture hobby). I've got some spares around, maybe I'll drop one into some 170F water and see how soft they get. The pp ones work fine on the tun though....

I tried using a gray pvc pipe nipple on my HLT and is started to sag like a cooked noodle when it was exposed to 180*F sparge water. I don't know what the working temperature of the gray pvc is, but up in that range it will get really soft. At boiling temps I think you might be able to pour it. CPVC can handle the higher temps, but not regular PVC.